“JSA” is not very plausible. The movie’s scenes of free and easy fraternization would be wildly unthinkable in real life. On the other hand, the North and the South may be on the cusp of a historic rapprochement–and that has sparked interest in this movie. Two weeks ago Pyongyang announced that early next year the North’s leader, Kim Jong Il, will visit Seoul. And in Sydney, North and South Korean athletes wearing identical national uniforms marched hand in hand in the Olympic opening ceremonies. What’s left? Just for starters, maybe Pyongyang could decide to let Northerners see “JSA.” They’ve never seen a movie like it either.